Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933206AbZKXO5T (ORCPT ); Tue, 24 Nov 2009 09:57:19 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S933133AbZKXO5S (ORCPT ); Tue, 24 Nov 2009 09:57:18 -0500 Received: from www.tglx.de ([62.245.132.106]:54710 "EHLO www.tglx.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933126AbZKXO5S (ORCPT ); Tue, 24 Nov 2009 09:57:18 -0500 Date: Tue, 24 Nov 2009 15:55:49 +0100 (CET) From: Thomas Gleixner To: Andrew Haley cc: "H.J. Lu" , rostedt@goodmis.org, Ingo Molnar , "H. Peter Anvin" , LKML , Andrew Morton , Heiko Carstens , feng.tang@intel.com, Peter Zijlstra , Frederic Weisbecker , David Daney , Richard Guenther , jakub@redhat.com, gcc , Linus Torvalds Subject: Re: [PATCH][GIT PULL][v2.6.32] tracing/x86: Add check to detect GCC messing with mcount prologue In-Reply-To: <4B0BF119.4070704@redhat.com> Message-ID: References: <20091119072040.GA23579@elte.hu> <1258694593.22249.1012.camel@gandalf.stny.rr.com> <1258736456.22249.1032.camel@gandalf.stny.rr.com> <4B06EF6F.2050507@redhat.com> <6dc9ffc80911220138y15bfa91agccf5c29f1c30e09a@mail.gmail.com> <4B0972C9.302@redhat.com> <6dc9ffc80911221530t38d83cf6je739743c8d756667@mail.gmail.com> <4B0BF119.4070704@redhat.com> User-Agent: Alpine 2.00 (LFD 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2417 Lines: 62 On Tue, 24 Nov 2009, Andrew Haley wrote: > H.J. Lu wrote: > > On Sun, Nov 22, 2009 at 9:20 AM, Andrew Haley wrote: > >> H.J. Lu wrote: > >>> On Fri, Nov 20, 2009 at 11:35 AM, Andrew Haley wrote: > >>>> Steven Rostedt wrote: > >>>>> Ingo, Thomas and Linus, > >>>>> > >>>>> I know Thomas did a patch to force the -mtune=generic, but just in case > >>>>> gcc decides to do something crazy again, this patch will catch it. > >>>>> > >>>>> Should we try to get this in now? > >>>> I'm sure this makes sense, but a gcc test case would be even better. > >>>> If this can be detected in the gcc test suite it'll be found and > >>>> fixed long before y'all in kernel land get to see it. That's the > >>>> only way to guarantee this never bothers you again. > >>>> > >>>> H.J., who wrote the code in question, is hopefully looking at why > >>>> this odd code is being generated. Once he's done I can put a > >>>> suitable test case in the gcc test suite. > >>>> > >>> See: > >>> > >>> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42109#c7 > >> I saw that, but does it mean you're going to investigate? There is > >> no obvious reason why -mtune=generic should affect code generation > >> in this way, but it does. > > > > Why not, there is > > > > static const unsigned int x86_accumulate_outgoing_args > > = m_AMD_MULTIPLE | m_ATOM | m_PENT4 | m_NOCONA | m_PPRO | m_CORE2 > > | m_GENERIC; > > > > -mtune=generic turns on -maccumulate-outgoing-args. > > Alright, so let's at least try to give the kernel people the information > that they need. > > What you're saying is, to avoid this: > > 000005f0 : > 5f0: 57 push %edi > 5f1: 8d 7c 24 08 lea 0x8(%esp),%edi > 5f5: 83 e4 f0 and $0xfffffff0,%esp > 5f8: ff 77 fc pushl -0x4(%edi) > 5fb: 55 push %ebp > 5fc: 89 e5 mov %esp,%ebp > > you should compile your code with -maccumulate-outgoing-args, and there's > no need to use -mtune=generic. Is that right? Seems to work. What other side effects has that ? Thanks, tglx -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/